EP0548316B1 - Hydrostatically supported sag-compensation roller, in particular for paper-manufacturing machines - Google Patents

Abstract

PCT No. PCT/EP92/01562 Sec. 371 Date Mar. 12, 1993 Sec. 102(e) Date Mar. 12, 1993 PCT Filed Jul. 10, 1992 PCT Pub. No. WO93/01351 PCT Pub. Date Jan. 21, 1993.The invention relates to a sag-compensation roll having a roll shell (1), a stationary yoke (2), and an oblong hydrostatic pressure shoe (8) which can be tilted about a longitudinal axis and contains hydrostatic pressure pockets (11, 12). The pressure shoe is fitted to the inside diameter of the roll shell (1) and is attached to a radially movable oblong piston (4) which is sealed off from the yoke (2). The longitudinal ridges (9, 10) which define the individual hydrostatic pockets (11, 12) have a width (a, b) equal to at most 1/20 of the width (K) of the piston. The pressure shoe (8) is hydraulically supported over the main part of its width on its lower side, i.e. the side which faces the yoke (2).

Description

The invention relates to a deflection compensation roller for treating a running web, e.g. Paper web, with the features specified in the preamble of claim 1. It is therefore a roller with a rotatable roller shell, and with a stationary yoke and with at least one radially displaceable elongate pressure shoe, which is used to transmit a pressing force from the roller shell to the yoke.

The pressure shoe has pressure pockets which are delimited by surrounding web surfaces which are adapted to the contour of the inner surface of the roller tube. An oil flow conveyed into the pressure pockets means that a gap is created between the jacket and the web surfaces through which the oil flows.

Rollers are known e.g. with a variety of pressure shoes distributed over the web width (= roll length) e.g. according to DE 22 45 597 = US 3,846,883. Other known rollers have only a few, in extreme cases only a single, elongated pressure shoe which extends parallel to the roller axis, e.g. according to US 3,802,044 (Fig. 6 and 7) or according to DE 25 02 161 = GB 1506801 (file P 3361). In the latter embodiment, the pressure shoe containing the pressure pockets is pressed against the roller jacket by a piston via a joint bar. The pressure shoe contains a long, relatively wide central pocket, which is surrounded on both sides by narrow positioning pockets.

The positioning pockets are divided into several sections in the longitudinal direction by intermediate webs. In everyone this section opens into a capillary extending from the central pocket through which the oil flows, which determine the gap width between the webs and the roller jacket. The internal line force exerted on the roller jacket is determined by the product of piston width times hydraulic pressure on the piston.

A disadvantage of such hydrostatic rollers compared to the conventional S roller (according to DE 11 93 739 = US 3,196,520) or a roller with a plain bearing shoe (according to DE 21 65 118 = US 3,726,338) is that the pressure medium (oil) constantly escapes through the capillaries and gaps . As a result, a higher power consumption is required to deliver the pressure oil that flows off again and again because the power increases proportionally with the product of the hydraulic pump pressure and the flow rate.

Another disadvantage, which is particularly noticeable at high running speeds, is the loss of performance due to the shear forces in the oil in the area of the narrow gaps between the roller jacket and the webs of the hydrostatic elements.

Attempts have already been made to reduce both power consumption (reactive power), e.g. by choosing a thinner oil and narrower gaps. The capillaries then become so small that they become blocked by sporadic dirt particles. The webs may also rub against the roller shell.

For these reasons, since the introduction of the hydrostatic deflection compensation rollers about 20 years ago, it has become common to make the web widths large and the pressures high when using a high-viscosity oil, for example VG 150 or VG 220. This made it possible to reduce the oil quantities with enough large capillaries and gap widths, but you had to put up with a relatively high internal friction.

It is the main object of the present invention to redesign a hydrostatically operating deflection compensation roller in such a way that the reactive power (= pump output plus power loss due to internal friction) is reduced to a fraction of the values customary today.

Other tasks are simple, cost-saving construction and equal temperature distribution across the web width. In addition, proper functioning of all parts must be ensured, in particular the hydrostatic elements must function in all installation positions relative to the direction of gravity.

It is also important that the pressure shoe deflects as little as possible under load so that the gap widths on the webs (which delimit the pressure pockets) change as little as possible.

In addition, the pressure shoe should weaken the yoke cross section as little as possible so that the roller diameter does not have to be made unnecessarily large (cost, weight).

Finally, the pressure shoe should be thermally stable, i.e. it must not become crooked due to uneven heating of the webs across the width as a result of accelerating heating in the zones of narrowing gap widths.

The main task is solved by the features of claim 1.

According to the invention, the amount of pressure medium escaping from the pressure pockets (and thus the pump drive power) The following measures keep it relatively small: Instead of a large number of small pressure shoes, only a single elongate pressure shoe is used, or only a few, elongated pressure shoes forming a row are provided, which extend essentially parallel to the roller axis. As a result, the ratio between the total length of the webs and the sum of the pressure pocket areas is kept relatively small. Another measure to reduce the pump drive power is that the effective width of the pressure chamber - in relation to the inner diameter of the roll shell - is unusually large, so that one can manage with a relatively low pressure medium pressure. In this context, it is important to keep the overall width of the pressure shoe as small as possible; According to the invention, this total width is at most 1.3 times the effective width of the printing space. This takes into account that the pressure shoe - due to the large effective width of the pressure chamber - is given an essentially plate-like shape. It is now important that the pressure shoe, in spite of this plate-like shape - seen in cross section - does not suffer any (or only an extremely slight) deflection under load. To solve this subtask, the already mentioned limitation of the total width of the pressure shoe and a hydraulic support of the underside of the pressure shoe facing the yoke (as will be explained in detail below). As a result of these measures, it can be expected that the dimensional accuracy of all gaps between the webs and the roll shell will be maintained with high accuracy during operation, even with relatively large changes in the line force.

Another crucial factor is the very small width of the webs, which reduces the internal friction loss of the roller.

In retrospect, the surprising result that, despite the extreme reduction in the web width, no higher pump output is required is based on the fact that with the same web width and gap width v̇∼p (laminar flow) and the power P∼p x v̇, i.e. P∼p! (P = pump power, p = pump pressure, v̇ = flow rate) e.g. by increasing the piston area to three times, the required pressure drops to 1/3 with the same line force and the necessary pump output to 1/9 if the web widths remain the same.

However, it is also possible to reduce the web width to 1/9 of the previous value with the same pump output, with a correspondingly drastically reduced internal friction output.

Such a design of the hydrostatic pressure shoe, which at first appears to be contradictory, actually enables an enormous reduction in the reactive power of a hydrostatically supported deflection compensation roller.
In other words, both the pump power and the power to drive the roller can be drastically reduced.

The above-mentioned hydraulic support of the underside of the pressure shoe can be realized in different ways: If the pressure shoe is connected to a separate piston by means of an articulated bar, a space is sealed between the pressure shoe and the piston according to the invention, in which there is approximately the same pressure as the interior of the roller in the pressure room. Deviating from this, however, the construction according to the invention can be significantly simplified in that the pressure shoe and the piston form an integral component; in other words: the pressure shoe is also designed as a piston. In this case, the hydraulic support the underside of the pressure shoe guaranteed by the pressure prevailing in the pressure chamber. In all cases it is achieved that a deflection of the relatively wide shoe is avoided by an at least approximately equal pressure on both sides (top and bottom) of the pressure shoe.

The one-piece pressure shoe, which is also designed as a piston, can be tilted by means of a short guide length and piston bed in the area of the longitudinal seal. The sealing can be done either by elastic sealing lips or by rigid strips e.g. according to DE 35 03 371 = US 4,651,628 (file P 4183), paying particular attention to the large stroke of the face seal.

The design of the pressure shoe with a wide central chamber and narrow outer hydraulic pockets is preferred (DE 25 02 161). This design is particularly advantageous for large shoe widths because it is less sensitive to changes in gaps over the individual longitudinal webs than a design with a central web and two outer webs.

A further reduction in reactive power is achieved by making the inner webs between the middle chamber and hydrostatic pockets narrower than the outer webs. This can happen because the pressure difference and thus the oil flow through these webs is small.

In a preferred embodiment, the outer webs are approximately 1.5 to 2.5 times wider than the inner webs.

Furthermore, hydrostatic pressure pockets supplied with oil via capillaries are also provided on the end faces of a pressure shoe. In this way it is ensured that the higher occurring there in a ring zone Friction power does not lead to local heating. The frictional heat is washed away by the hydrostatic oil. These end strips are similarly narrow as the longitudinal strips.

On the one hand, the pressure shoe should not be too bulky and heavy, on the other hand, sufficient flexural rigidity is necessary. The essentially plate-shaped pressure shoe should, in order to meet the demands placed on it, have a thickness at least in the region of its central axis which is 0.15 to 0.3 times the width. On the one hand, this ensures that the yoke is not weakened too much and, on the other hand, that the rigidity required for precise gap maintenance is given. The pressure shoe is then still sufficiently elastic over the web width (i.e. over its length) to adapt in parallel to the roll jacket under the action of the hydrostatic forces.

It is also advantageous to work the hydrostatic pockets into strips that can be screwed onto the pressure shoe. This applies both to the longitudinal strips and to the front strips shaped like a segment of a circle.

In order to minimize thermal bending, an insulating layer is inserted between the pressure shoe and the last. This insulating layer is about 1 to 5 mm thick. It can consist of plastic or resin-bonded fabric layers.

The main part of the pressure shoe is preferably made of steel, the screwed last from a material with good sliding properties compared to the roller jacket made of steel or cast iron.

For example, if the pressure shoe presses upwards, then special pressure means must be provided that move it out of it Bring the rest position into the working position in close contact with the roller jacket. According to a further embodiment of the invention, this is done by pressing means which are independent of the hydraulic pressure, for example by prestressed springs.

If the pressure arrangement described is installed in an equidistantly mounted roller (according to DE 30 24 575 = US Re 32,586; file P 3795), which can also have the same bearing distance with the counter roller, several hydraulic pressure zones across the web width are generally superfluous . This makes the pressing device simple and cheap, because only a single pressing shoe is required, which extends over the entire web width.

If the pressure arrangement described is built into a self-pressing roller (according to DE 36 23 028 = US 4,691,421 file P 4285), then as a rule several pressure shoes distributed over the web width and counter pressure shoes are provided on the roller ends.

Figur 1

ist ein Teilquerschnitt durch eine Durchbiegungsausgleichswalze mit hydrostatischer Anpreßanordnung.

Figur 2

ist eine Ansicht der Anordnung von Figur 1 in Pfeilrichtung R.

Figur 3

ist ein Querschnitt durch eine andere Anpreßanordnung.

Figur 4

ist eine Alternative zu Figur 3.

Figur 5

ist ein Längsschnitt entlang der Schnittlinie V-V in Figur 4.

Figur 6

ist ein schematischer Längsschnitt durch eine äquidistant gelagerte Durchbiegungsausgleichswalze.

Figur 7

ist ein schematischer Längsschnitt durch eine selbstanpressende Durchbiegungsausgleichswalze.

The invention is explained in more detail with reference to FIGS. 1-7.

Figure 1

is a partial cross section through a deflection compensation roller with a hydrostatic pressure arrangement.

Figure 2

is a view of the arrangement of Figure 1 in the direction of arrow R.

Figure 3

is a cross section through another pressure arrangement.

Figure 4

is an alternative to Figure 3.

Figure 5

is a longitudinal section along the section line VV in Figure 4.

Figure 6

is a schematic longitudinal section through an equidistant deflection compensation roller.

Figure 7

is a schematic longitudinal section through a self-pressing deflection compensation roller.

In FIG. 1, 1 means a rotatably mounted roller jacket which is penetrated by a fixed yoke 2. An elongated bed 3 is incorporated into the yoke 2, in which an elongated piston 4 can move up and down. Elastic seals 5 are installed in the piston 4 and seal the pressure chamber 6 to the outside. Its effective width K is approximately 0.4 times that of the roll jacket internal pressure gauge.

A pressure shoe 8 (hereinafter referred to as “shaped piece”) is tiltably mounted on an elongated hinge pin 7 embedded in the piston 4. Whose total width B is about 1.2 times the width K of the pressure chamber 6, its thickness T about 0.16 times the width B. The shaped piece 8 carries two inner longitudinal webs 9 and two outer longitudinal webs 10, the hydrostatic pockets between them 11 form. Between the webs 9 there is a central chamber 12, in which there is essentially the same pressure as in the pressure chamber 6. The width a of the inner longitudinal webs 9 is approximately 1/80 and the width b of the outer longitudinal webs 10 is approximately 1/40 of the width K of the pressure chamber 6.

Between the piston 4 and the shaped piece 8 there is a further pressure chamber 13, which is sealed on the longitudinal side by sealing strips 16 held in grooves 14 and 15 and on the end face by sealing plates 17 (dashed lines).

Pressure medium enters the pressure chamber 6 through a supply line 18 and into the central chamber 12 via one or more bores 19 (penetrating the piston 4, hinge pin 7 and fitting 8). The pressure medium also reaches the pressure chamber 13 and from via transverse bores 20 in the hinge pin 7 this through the capillary bores 21 into the hydrostatic pockets 11.

As soon as the pressure in the hydrostatic pockets 11 has reached a certain level, in which the sum of the hydraulic forces between the roller jacket 1 and the fitting 8 corresponds to the hydraulic force of the pressure medium in the space 6 on the piston 4, an oil-filled gap is formed between the roller jacket 1 and the Crosspieces 9, 10 of the fitting 8. This ensures that the jacket 1 runs without wear. The roller shell 1 can rotate either clockwise or counterclockwise. At both ends, the roller jacket 1 is positioned relative to the yoke 2 in a known manner by roller bearings, not shown.

FIG. 2 shows the shaped piece 8, the longitudinal strips 9 and 10 and transverse webs 22 separating adjacent hydrostatic pockets 11. In addition, a capillary 21 opens into each hydrostatic pocket. The oil is added through the bore 19.

In FIG. 3 there is a fixed yoke 32 within a rotatably mounted roller shell 31. A pressure shoe 33 is mounted in the yoke 32, which also has the function of a piston and which is vertically movable and is sealed with respect to the yoke 32 by elastic seals 34. Seals are also located on the end face between yoke 32 and pressure shoe 33, as indicated by dashed lines at 35. Sealing strips 36 with integrated hydrostatic pockets 37 are screwed onto the pressure shoe 33 by means of screws 39 with the interposition of an insulating material plate 38.

Sealing strips 40 are screwed onto the pressure shoe 33 at both ends. Hydrostatic pockets 41 (dashed lines) are also incorporated into these sealing strips 40 and are supplied with pressure medium via capillaries 42. The hydrostatic pockets 37 are supplied with pressure medium through capillary bores 43 (in some of the fastening screws 39). The pressure medium passes through the feed bore 44 into the pressure chamber 45 and through openings 46 to the roller jacket 31. The total width B of the pressure shoe 33 is approximately 1.1 times the effective width K of the pressure chamber 45. The hydrostatic pockets 37 are similar to in Figure 2, divided by intermediate webs 47 across the web width into several sections.

In Figure 4 , a rotatably mounted roller shell 51 and a yoke 52 can be seen in partial section.

Sealing strips 53 with integrated hydrostatic pockets 54 are connected by an intermediate plate 55 and screws 56. Face sealing plates 57 are also screwed to the sealing strips 53 with connecting screws, not shown. The intermediate plate 55 either has pressure medium bores 58 or consists of several parts with spaces.
Seals 59 prevent pressure medium from escaping between yoke 52 and sealing strips 53.

Springs 60 press the pressure shoe consisting of the parts 53 to 56 against the roller shell 51.

The spring force of the springs 60 is such that it compensates for the weight of the parts 53-56 and overcomes the sealing friction.

Pressure medium enters the pressure chamber 62 through a pressure medium line 61 and into the hydrostatic pockets 54 via capillary bores 63.

FIG. 5 again shows the rotatably mounted roller shell 51, the yoke 52, sealing strip 53 and end seal 57, and the intermediate plate 55, designed in the form of individual square bars 55 '.

A horizontally movable end sealing strip 64 is guided in a sealing strip holder 66 fastened to the yoke 52. It is pressed against the face seal 57 by springs 65. The pressure medium passes through the supply line 61 into the pressure chamber 62 and through capillaries 63 into the invisible hydrostatic pockets 54 of the longitudinal sealing strips 53 and via capillaries 67 into the hydrostatic pockets 68.

As an alternative to the springs 60 shown in FIG. 4, the pressing unit can also be raised for the first time by fluidic pressure, e.g. by briefly reducing or closing the bore 19 in FIG. 1 with the aid of a time-controlled valve or the like.

Alternatively, separate oil feeds into rooms 6 and 12 of FIG. 1 would also be conceivable for this purpose. The spaces 13 could alternatively be connected to the pressure space 6 by means of direct holes instead of the holes 19 and 20.

FIG. 6 shows an equidistantly set deflection adjustment roller, which largely corresponds to that according to FIGS. 4 and 5. There is a single elongated pressure shoe, of which the parts 53, 55 'and 57 are visible.

The roller shell 51 has a bearing neck 70 at both ends, which is mounted in a support block 72 by means of roller bearings 71. The stationary yoke 52 also rests in the support stands 72 by means of spherical bushes 73. The distance LE between the center planes of the roller bearings 71 and the bushes 73 is the same. The remaining details are provided with the same reference numbers as the corresponding parts in FIGS. 4 and 5.

FIG. 7 shows a deflection adjustment roller that differs from FIG. 6. It comprises a rotatable roller jacket 81, a stationary yoke 82 and a plurality of elongate pressure shoes 83 arranged in a row. A drive ring 80 rotates with the roller jacket 81 and a toothed ring 79 fastened thereon, which meshes with a non-visible drive pinion. A gear housing 78 is mounted on the ring gear 79 by means of roller bearings 77. The yoke 82 rests in a support frame 84. The roller shell 81 is mounted on a so-called link 86 with the aid of a roller bearing 85. This cannot be rotated, but can be displaced in the radial direction relative to the yoke 82. Thus, the roller shell 81 (together with the elements 77-80 mentioned) can be displaced in the radial direction relative to the yoke. It can, for example, be lifted from a counter-roller (not shown) and put on and pressed against it. In Fig. 7 it is a so-called self-pressing roller. The end of the roller that is not visible in FIG. 7 is essentially the same as the visible end; only the drive elements 77 to 79 are missing. Deviating from FIG. 6, the distance between the roller bearings 85 of the roller shell 81 is considerably smaller than the distance between the bearings of the yoke 82 in the support blocks 84. It is therefore advantageous to separate each pressure shoe 83 from separate ones Pressure lines 87 with different pressures charge. In addition, at least one counter-pressure shoe 88 is provided at each roller end, which is pressurized via an additional pressure line 89.

Claims (16)

1. A sag-compensating roller, in particular for paper machines, with the following features:

   a) a stationary yoke (2) extends through the interior of a rotatable roller casing (1);

   b) at least one oblong press-on shoe (8; 33; 53-57), which extends parallel to the roller axis and the outside contour of which is matched to the inside surface of the roller casing and which is movable radially to the yoke and tiltable around its longitudinal axis, is located between the roller casing (1) ) and the yoke (2);

   c) the press-on shoe has hydrostatic pressure pockets (11, 12) in its outside contour for the purpose of transferring a pressure load from the roller casing (1) to the yoke (2); furthermore, a pressure area (6; 45; 62) is provided between the press-on shoe and the yoke;

   characterized by the following features:

   d) the operational width (K) of the pressure area (6; 45; 62) is at least 0.2 times the inside diameter of the roller casing (1);

   e) the overall width (B) of the press-on shoe (8; 33; 53-57) is maximum 1.3 times the operational width (K) of the pressure area;

   f) the bottom side of the press-on shoe (8; 33; 53-57) which is oriented towards the yoke (2) is hydraulically supported;

   g) the longitudinal webs (9, 10) which define the pressure pockets (11, 12) have a width (a, b) of maximum 1/20 of the operational width (K) of the pressure area (6; 45; 62).
2. A sag-compensating roller according to claim 1, characterized in that the operational width (K) of the pressure area (6; 45; 62) is between 0.25 and 0.5 times the inside diameter of the roller casing (1).
3. A sag-compensating roller according to claim 1 or 2, characterized in that the width (a, b) of the longitudinal webs (9, 10) is between 1130 and 1/100 of the width (K) of the pressure area (6; 45; 62).
4. A sag-compensating roller according to claim 1, 2 or 3, characterized by the following features:

   a) the press-on shoe (8) is connected by means of a hinged ledge (7) to a separate piston (4) which defines the pressure area (6) towards the remaining inner area of the roller;

   b) an intermediate space (13), which is sealed from the remaining inner area of the roller and the inside pressure of which is virtually the same as that in the pressure area, is present between the press-on shoe (8) and the piston (4).
5. A sag-compensating roller according to claim 1, 2 or 3, characterized in that the press-on shoe (33) is also designed as a piston, which defines the pressure area (45) towards the remaining roller inside area and which is tiltable around an imaginary longitudinal axis in the pressure area (45).
6. A sag-compensating roller according to one of claims 1 to 5, characterized in that on both sides of a central chamber (12), which is essentially of machine width, are arranged narrow pressure pockets (11) of machine width which are supplied with oil via capillaries (21).
7. A sag-compensating roller according to claim 6, characterized in that the width (b) of the outer webs (10) between pressure pockets (11) and roller inside area is larger than the width (a) of the inner webs (9) between pressure pockets (11) and central chamber (12).
8. A sag-compensating roller according to claim 7, characterized in that the outer webs (10) are approximately twice as wide as the inner webs (9).
9. A sag-compensating roller according to one of claims 1 to 8, characterized in that pressure pockets which are supplied with oil via capillaries (67) are also present at the ends.
10. A sag-compensating roller according to one of claims 1 to 9, characterized in that the press-on shoe (8; 33) comprises a predominantly plateshaped portion with a cross-sectional thickness/width ratio (T/B) of 0.15 to 0.33.
11. A sag-compensating roller according to one of claims 1 to 10, characterized in that ledges (36; 53) containing pressure pockets (37; 54) are bolted onto an elongated support element (33; 55)
12. A sag-compensating roller according to claim 11, characterized in that an insulating layer (38) is fitted between the ledges (36) and the support element (33).
13. A sag-compensating roller according to claim 11 or 12, characterized in that the support element (33; 55) is made of steel, and the ledges (36; 53) are made of a material with better slide properties than steel or cast iron.
14. A sag-compensating roller according to one of claims 1 to 13, characterized in that press-on means (for example springs 60) are provided which push the shoe (53-56), even in its unpressurized state, against the force of gravity towards the roller casing (51).
15. A sag-compensating roller according to one of claims 1 to 14, characterized in that it is designed as an equidistantly mounted roller (i.e. the mounting distances (LE) of the rotatable casing (51) and the stationary yoke (52) are approximately identical) and that there is only one single press-on shoe (53-57) which extends essentially along the entire roller casing (51) (Fig. 6).
16. A sag-compensating roller according to one of claims 1 to 14, characterized in that it is designed as a roller which presses itself on (i.e. the roller casing (81) is radially displaceable relative to the yoke (82)), and that a plurality of oblong press-on shoes (83) arranged in a row is provided, the pressure areas of which are loadable with different pressures (Fig. 7).

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